Serum cytokine profiles of adults with idiopathic inflammatory myopathies

OBJECTIVES

There is a paucity of available biomarkers of disease activity in idiopathic inflammatory myopathies (IIM), and serum cytokines/chemokines hold potential as candidate biomarkers. We aimed to determine serum cytokine profiles of IIM patients with active disease as compared to patients in remission and healthy controls.

METHODS

The IIM patients with active disease (included patients enrolled in repository corticotropin injection trial), in remission, and healthy controls were enrolled in this cross-sectional observational study. Serum concentrations of 51 cytokines/chemokines were obtained by utilising a bead-based multiplex cytokine assay (Luminex®). The myositis core set measures were obtained for all the patients. Cytokines with the best predictive ability to differentiate these clinical groups were assessed with three methods: 1) Least Absolute Shrinkage and Selection Operator modelling, 2) stepwise approach, and 3) logistic regression model.

RESULTS

Twenty-one IIM patients with active disease, 11 IIM patients in remission and 10 healthy controls were enrolled. Myositis patients had elevated levels of chemokines that attract eosinophils (eotaxin) and dendritic cells, NK cells, cytotoxic T-cells and monocytes/macrophages (CXCL-9, IP-10), cytokines that drive T-helper 1 responses (TNF-a, lymphotoxin-a), matrix degrading enzymes (MMP-3 and -9), and IGFBP-2 compared to healthy controls. Myositis patients with active disease had higher levels of lymphotoxin-a, CXCL-9, MIP-1a, MIP-1b and MMP-3 than patients in remission.

CONCLUSIONS

This study demonstrated differences in cytokine profiles of IIM patients (active and inactive disease) compared to healthy controls and identified some cytokines that could potentially be used as biomarkers. Larger longitudinal studies are needed to validate our findings.

Utility of patient-reported outcomes measurement information system (PROMIS) physical function form in inflammatory myopathy

OBJECTIVE

Idiopathic inflammatory myopathies (IIM) are a group of diseases characterized by muscle weakness, which limit activities of daily living. Patient Reported Outcomes Measurement Information System (PROMIS) is a set of outcome measures developed using NIH funding, but has not yet been studied in adult IIM. Currently, the most commonly used PROs in IIM are Health Assessment Questionnaire (HAQ-DI) and SF-36 physical function-10 (PF10), both of which have several limitations. In this study, we investigated psychometric properties of PROMIS physical function-20 (PF-20) and compared to HAQ-DI and SF-36 PF10.

METHODS

Patients with IIM completed PROMIS PF-20 and six myositis core set measures [manual muscle testing (MMT), physician (MD-GDA), patient (PT-GDA) and extra-muscular global disease activity, HAQ-DI and creatine kinase], SF-36 PF10 and functional tests [six-minute walk, timed up-and-go and sit-to-stand tests] at monthly visits over 6-months. Total improvement score (TIS) using 2016 ACR/EULAR myositis response criteria was obtained as measures of change.

RESULTS

Fifty patients [mean age, 51.6; 60% females] were enrolled; 6 PM, 24 DM, 9 NM and 11 with AS. PROMIS PF-20 showed strong test-retest reliability when repeated in 1-month. PROMIS PF-20 had moderate-strong correlations with MD-GDA, PT-GDA, MMT, HAQ-DI, SF-36 PF10, and functional tests indicating good convergent validity. Change in PROMIS PF-20 strongly correlated with TIS demonstrating good responsiveness. HAQ-DI and SF-36 PF10 exhibited similar validity and responsiveness; HAQ-DI was found to have a ceiling effect.

CONCLUSION

PROMIS PF-20 demonstrates favorable psychometric properties in a large cohort of myositis patients and offers distinct advantages.

Reliability, Validity and Responsiveness of Physical Activity Monitors in Patients with Inflammatory Myopathy

OBJECTIVE

Idiopathic inflammatory myopathies (IIM) cause proximal muscle weakness, which affect activities of daily living. Wearable physical activity monitors (PAMs) objectively assess continuous activity with potential clinical usefulness in IIM assessment. We examined the psychometric characteristics for PAM outcomes in IIM.

METHODS

Adult IIM patients were prospectively evaluated (baseline, 3 and 6-months) in an observational study. A waist-worn PAM (ActiGraph GT3X-BT) assessed average step counts/min, peak 1-min cadence, and vector magnitude/min. Validated myositis core set measures (CSM) including manual muscle testing (MMT), physician global disease activity (MD global), patient global disease activity (Pt global), extra-muscular disease activity (Ex-muscular global), HAQ-DI, muscle enzymes, and patient-reported physical function were evaluated. Test-retest reliability, construct validity, and responsiveness were determined for PAM measures and CSM using Pearson correlations and other appropriate analyses.

RESULTS

50 adult IIM patients enrolled [mean (SD) age, 53.6 (±14.6); 60% female, 94% Caucasian]. PAM measures showed strong test-retest reliability, moderate-to-strong correlations at baseline with MD global (r=-0.37- -0.48), Pt-global (r=-0.43- -0.61), HAQ-DI (r=-0.47- -0.59) and MMT (r = 0.37-0.52), and strong discriminant validity for categorical MMT and HAQ-DI. Longitudinal association with MD global (r=-0.38- -0.44), MMT (r = 0.50-0.57), HAQ-DI (r=-0.45- -0.55), and functional tests (r = 0.30-0.65) were moderate-to-strong. PAM measures were responsive to MMT improvement (≥10%) and moderate-to-major improvement on ACR/EULAR myositis response criteria. Peak 1-min cadence had the largest effect size and Standardized Response Means (SRMs).

CONCLUSION

PAM measures showed promising construct validity, reliability, and longitudinal responsiveness; especially peak 1-min cadence. PAMs provide valid outcome measures for future use in IIM clinical trials.

Follow-up results of myositis patients treated with H. P. Acthar gel

OBJECTIVES

Idiopathic inflammatory myopathies (IIM) are a group of autoimmune diseases characterized by proximal muscle weakness. H. P. Acthar gel [repository corticotropin injection (RCI)] is a formulation of adrenocorticotropic hormone and has been approved by Food and Drug Administration for use in IIM; however, literature is limited. In this study, we report longitudinal follow-up of myositis patients treated with RCI.

METHODS

Patients with refractory IIM who were enrolled in the prospective, open-label RCI trial were included in this study. The post-trial follow-up period was 6 months with assessments every 2 months, which included myositis core set measures including extra-muscular global, muscle and patient global disease activities, HAQ, and manual muscle testing.

RESULTS

Two patients were lost to follow-up after finalization of the trial, and the remaining eight patients were enrolled in the follow-up study. One patient remained on RCI after the trial. In the follow-up period, four of eight patients had flare at on average 4.1 months after the RCI trial. Among the patients who flared, three required an increase in prednisone. One patient was restarted on RCI at 5.5 months, but had minimal improvement after 3 months. Four patients who remained stable continued to satisfy criteria for the definition of improvement through the 6-month follow-up. However, none showed any further improvement in the primary or secondary efficacy outcomes after the initial RCI trial.

CONCLUSION

To our knowledge, this is the first study reporting the follow-up results of patients treated with standard dose and duration of Acthar. We believe that our study will provide the basis for the development of future randomized RCI trials in IIM.